On Mon, Jul 30, 2018 at 06:07:47PM +0000, Jeremy Cline wrote:
'ac->ac_g_ex.fe_len' is a user-controlled value which is used in the derivation of 'ac->ac_2order'. 'ac->ac_2order', in turn, is used to index arrays which makes it a potential spectre gadget. Fix this by sanitizing the value assigned to 'ac->ac2_order'. This covers the following accesses found with the help of smatch:
fs/ext4/mballoc.c:1896 ext4_mb_simple_scan_group() warn: potential spectre issue 'grp->bb_counters' [w] (local cap)
fs/ext4/mballoc.c:445 mb_find_buddy() warn: potential spectre issue 'EXT4_SB(e4b->bd_sb)->s_mb_offsets' [r] (local cap)
fs/ext4/mballoc.c:446 mb_find_buddy() warn: potential spectre issue 'EXT4_SB(e4b->bd_sb)->s_mb_maxs' [r] (local cap)
Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: stable@vger.kernel.org Suggested-by: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Jeremy Cline jcline@redhat.com
Thanks, applied.
- Ted